The period from 06/01/81 to 05/31/82 will be concerned with: a. To perform N-terminal amino acid sequencing of the TL and QA-2 molecules. b. To comparatively peptide map TL, QA-2 and H-2. c. To isolate and sequence common peptides shared between TL, QA-2 and H-2. d. To determine the structural basis of polymorphism in the TL system. e. To determine whether there is polymorphism in the QA-2 system.